1. Technical Field
The present invention relates to an underwater remote inspection device and a method for underwater remote inspection, and more particularly, to an underwater remote inspection device and a method for underwater remote inspection suitable for inspecting a surface condition of a reactor internal of a boiling water reactor and a pressurized water reactor.
2. Background Art
As a device for inspecting the presence of a crack on a surface of a reactor internal installed in a nuclear reactor of a nuclear plant, an underwater remote inspection device has been known. Some examples of the underwater remote inspection device are described in Japanese Patent No. 3890239 and Japanese Patent Laid-open No. 2003-255074. The underwater remote inspection devices described in these publications have an etching device and a replica sampling device. The etching device includes electrode members and an electrolytic etchant supply device. An electrolytic etchant (oxalic acid) comes in contact with a surface to be inspected of a reactor internal, and the surface is etched by applying electricity to the electrode members. By etching the inspection surface of the reactor internal, the surface is corroded, making the grain boundaries of the metal structure of the surface easier to see. After the etching is completed, the replica sampling device is used to sample a replica of the etched surface.
Japanese Patent Laid-open No. 9(1997)-89786 discloses an underwater remote inspection device in which, an etchant (oxalic acid) soaked into a sponge is applied to a surface to be inspected of a reactor internal and the surface is etched. Using a magnifying camera provided to the underwater remote inspection device, an image is taken of the metal structure of the etched surface to be inspected of the reactor internal. The magnifying camera has a magnifying lens capable of enlarging the image to a few hundreds of times the standard, allowing the enlarged image of the metal structure to be taken. The image of the metal structure taken by the magnifying camera is displayed on a monitor so that any over sensitization in the inspection surface can be checked.